The nature of the concentration fluorescence quenching of Nd3+ in silicate glasses, which is associated with the reaction Nd3+ (formula) has been reinvestigated by monitoring the fluorescence intensity of Nd3+ at 1060nm as a function of time. The experimental decay curves were compared with theoretical ones, based upondipole-dipole, dipole-quadrupole and quadrupole-quadrupole interactions. The latter two interaction models appear to predominate in deexciting Nd3+. Their relative contributions depend upon the [Nd3+].At higher [Nd3+] rare earth ions having another Nd3+ ion as a nearest neighbour, namely ion 'pairs', may give rise to possible contribution of exchange interactions through a rapid electronic excitation energy migration from an excited Nd3+ ion to such pairs.
